Tens of millions of air filters are manufactured every year for use with internal combustion engines. Internal combustion engines used to power vehicles necessarily consume dust-laden air during their operation. The dust must be removed from the air in order to have acceptable engine life. Over time, the air filters become clogged with dust and are periodically replaced. As a filter becomes clogged, it causes an increase in fuel consumption and a decrease in engine power which combine to increase air pollution.
Air filters used with internal combustion engines tend not to have an even distribution of dust and debris over their surfaces which tends to decrease their efficiency and reduce their capacity. Overall filter performance is a combination of efficiency capacity and restriction. It has been found that as capacity and efficiency are increased restriction also increases, which has deleterious effects on engine performance. Consequently, increasing efficiency and capacity in current filters does not necessarily result in an advantage because if restriction is unacceptably increased, then power decreases and fuel consumption increases with the invariable result that air pollution increases. The increase in air pollution from a single vehicle is not significant; however, slight increases in air pollution from an entire fleet of vehicles, such as the vehicles operating in an urban area combine to create an environmental hazard.
By increasing capacity while increasing or at least not reducing efficiency and by maintaining acceptable restriction, the filter life is extended so that when air filters are periodically changed in accordance with a maintenance schedule, they are changed before restriction becomes unacceptable. Moreover, since filters last longer, there is ultimately less waste to dispose of, which in itself reduces environmental impact as well as irritation to businesses and people who service vehicles.
While improving efficiency and capacity of air filters used for internal combustion engines is a major concern addressed by the present invention, it is to be understood that increasing efficiency and capacity without unacceptably increasing restriction is also desirable in other types of filters, such as air and gas filters used in air conditioning systems and industrial plants, and in filters such as panel-type filters used to filter liquids.